Free area of the Republic of China
The Free area of the Republic of China is a legal and political description referring to the territories under the actual control by the government of the Republic of China (ROC), consisting of the island groups of Taiwan, Penghu, Kinmen, Matsu and some minor islands. As the island of Taiwan is the main component of the whole area, it is therefore also referred to as the "Taiwan Area of the Republic of China" or simply the "Taiwan Area". The term "Tai-Peng-Kin-Ma" is also essentially equivalent except that it only refers to the four main islands of the region - Taiwan, Penghu, Kinmen and Matsu, to the exclusion of the South China Sea area possessions.
The term is opposed to "mainland area of the Republic of China", which reflects the territory that was lost to the Chinese Communist Party following the Chinese Civil War and on which a separate state, the People's Republic of China (now commonly known as "China") was founded in 1949. This term is used in the "Additional Articles to the Constitution of the Republic of China".
The term "free area" or "Free China" was used during the Second Sino-Japanese War (1937–45) to describe the territories under the control of the Kuomintang (KMT) government in Chongqing (at the time romanised as Chungking) (as opposed to the parts of China under Japanese occupation, including Nanjing (Nanking) the capital of the Republic of China until the Japanese invasion in 1937).
...
Wikipedia